1. Field of the Invention
The invention relates to motor powered trowels for smoothing concrete.
2. Description of the Prior Art
It is known to be desirable to incorporate means in a power operated trowel enabling the blades to be tilted relative to the work surface to vary the blade action, for example, from a finishing action to a floating action or vice versa. U.S. Pat. Nos. 2,351,278 and 3,412,657 teach, for example, mechanical arrangements for adjusting the blade tilt whereas U.S. Pat. Nos. 2,826,971 and 3,062,107, by way of example, illustrate blade tilting apparatus using hydraulic mechanisms.
The ability to mechanically or hydraulically adjust the blade tilt provides the important advantage of being able to conduct both finishing and floating operations with the same blades by adjusting the tilt of the blades according to whether a finishing or floating action is desired. However, blades tend to wear very quickly because of the abrasive action between the blade surfaces and the concrete work surface. In some situations and depending on what type of action is required, i.e., floating or finishing, the blades can be reversed so that the original leading edges become the trailing edges of the blades and vice versa. However, substantial time is required to remove and replace or re-orient the blades.
As another aspect of motor powered trowel construction according to present practices, the set of trowel blades are always rotated in the same direction. The previously-mentioned prior art patents illustrate this unidirectional characteristic of motor powered trowels of the type having one set of trowel blades whereas U.S. Pat. Nos. 3,936,212 and 4,046,484 illustrate motor powered trowels having two or three sets of trowel blades but with each set always turning in the same direction. Thus, the blades, once mounted on their respective mounting arms, can only be rotated in one direction around the vertical drive shaft axis whereas the present invention recognizes that it would be desirable to have means enabling the set of blades to be rotated in either direction about the vertical drive axis as well as having means enabling the blades to be tilted in either direction around the radial horizontal axis of the respective mounting arms on which the blades are mounted in the typical motor powered trowel.
One of the most popular types of motor powered trowels is the type having only one set of trowel blades, as illustrated for example in U.S. Pat. No. 2,351,278, in contrast to a motor powered trowel having plural sets of blades as illustrated, for example, in U.S. Pat. No. 3,936,212. Since the motor powered trowel apparatus needs to be frequently moved from job site to job site, the ease of transport becomes an important consideration. In this regard, it is often desirable to have a motor powered trowel in which the overall diameter of the set of blades exceeds the width of the bed in the typical pickup truck. Thus, it would be desirable to have a motor powered trowel with a relatively large blade span but which could be folded for ease of transport in the bed of an ordinary pickup truck. Thus, the present invention has among other objects that of providing a motor powered trowel having means enabling the blades to be tilted in either direction as well as means enabling the blades to be rotated about the vertical drive axis in either direction together with means enabling the trowel structure to be folded for ease of transport. These and other objects will become apparent as the description proceeds.